JP2005330959A - Flap assembly for gas turbine engines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a divergent flap for a gas turbine engine for restricting plane detection. <P>SOLUTION: A divergent flap assembly 26 of a gas turbine engine is provided with a hot sheet 38, a backbone structure 40 for supporting the hot sheet, and a plow portion 46 fixed to the backbone structure 40 to bridge the gap between the hot sheet 38 and an external flap 24. The plow portion 46 is fabricated from CMC material, and has external geometry to complement and substantially continue geometry of the external flap 24 to minimize plane detection. The plow portion 46 is installed on the backbone structure 40 such that when the backbone structure 40 thermally expands, the plow portion 46 is shifted to minimize an offset between a trailing edge 58 of the hot sheet and the plow portion 46. The plow portion 46 is fixed to the backbone structure 40 by a plurality of fasteners 94 composed to minimize thermal stresses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas turbine engine, and more particularly to a branch flap of a gas turbine engine.

  Conventional gas turbine engines operate in extremely harsh environments characterized by extremely high temperatures and vibrations. A general gas turbine engine generates a thrust for propelling the engine by compressing inflow air, a combustor for mixing and burning the compressed gas coming out of the compressor with fuel, and expanding high-temperature gas. And a turbine for causing the hot gas to flow out of the engine. Thus, the exhaust nozzle must accommodate very high temperature gases exiting the engine.

  In military operations, the design of aircraft that avoids radar detection is an important issue. The ability of an aircraft to remain undetected, also called the signature of a plane, depends on the overall shape of the aircraft and the materials used to manufacture the aircraft. In order to minimize detection, it is desirable to eliminate gaps between engine members and to achieve a certain degree of smoothness with respect to the outer shape of the engine. In addition, it is desirable to refrain from using metal on the outer surface of the engine.

  Other considerations in engine design are to prevent air leakage and to insulate engine components from exposure to hot gases. One material that can withstand high-temperature gas is a ceramic matrix composite (hereinafter referred to as CMC) material. However, it is difficult to attach the CMC material member to the metal member. One of the obstacles in attaching a CMC member to a metal member is that the thermal expansion of these materials is different. It is usually difficult to attach or bond dissimilar materials in a gas turbine engine due to their different thermal expansion characteristics.

  According to the present invention, a branch flap assembly provided in an exhaust nozzle of a gas turbine engine includes a hot seat including a hot seat inner portion and a hot seat outer portion extending in the axial direction, A backbone structure for supporting the hot seat that is provided radially outside and in the vicinity of the outer portion of the hot seat; and a plow portion that is fixed to the backbone structure and that fills a gap between the hot seat and an external flap. . In order to minimize aircraft detection, the plow portion is made of CMC material and has an external shape that complements and substantially maintains the shape of the external flap. When the spine structure is thermally expanded, the plow portion is attached to the spine structure such that the plow portion moves and minimizes the offset between the trailing edge of the hot seat and the plow portion.

  According to an aspect of the present invention, the spine structure includes a plurality of openings, and some of the openings have a slot shape that allows relative movement between the spine structure and the hot seat. Thus, the plow portion moves in the axial direction when the backbone structure is thermally expanded.

  According to another aspect of the invention, the plow portion is secured to the spine structure by a plurality of fasteners configured to minimize thermal stress.

  According to another aspect of the invention, the flap assembly also includes a posterior support extending axially from the spine structure toward the trailing edge of the flap assembly to minimize deformation of the hot seat. including.

  These and other advantages of the present invention will become more apparent upon review of the embodiments described in the following detailed description and illustrated by the accompanying drawings.

  With reference to FIG. 1, the gas turbine engine 10 includes a compressor 12, a combustor 14, and a turbine 16 positioned about a central axis 17. The air 18 flows through the engine 10 in the axial direction. As is well known in the art, air 18 is compressed in compressor 12. Thereafter, in the combustor 14, the compressed air is mixed with fuel and burned. The hot gas expands while generating thrust, propelling the engine 10, driving the turbine 16, and then driving the compressor 12. The exhaust gas exiting from the turbine 16 flows out from the exhaust nozzle 20.

  Referring to FIG. 2, the exhaust nozzle 20 includes a plurality of external flaps 24 provided in the circumferential direction around the shaft 17 and a plurality of divergent flaps 26 provided radially inward from these external flaps. Including. Each of the outer flaps 24 includes an outer flap surface 28 having a special shape. Each branch flap 26 includes a front portion 30 and a rear portion 32. The front portion 30 includes a hinge assembly 36 that secures the branch flap 26 to the gas turbine engine. The branch flap 26 is provided with a hot sheet 38 extending from the front portion 30 to the rear portion 32 by the length of the flap 26, and is provided on the outer side in the radial direction of the hot sheet 38 and fixed to the hot seat 38 by the attachment means 42. It further includes a spine structure 40 and a plow portion 46 provided at the rear 32 of the branch flap 26 and secured to the spine structure 40 by a plow fastener assembly 48 shown in FIGS.

  With reference to FIGS. 3 and 4, in a preferred embodiment of the present invention, the hot sheet 38 includes a substantially flat substrate made from a ceramic matrix composite (CMC), which is connected to the exhaust gas 18. The exposed hot seat inner portion 50 and the hot seat outer portion 52 facing the spine structure 40 are included. The hot seat inner portion 50 and the hot seat outer portion 52 extend from the front portion 30 to the rear portion 32, and include a hinge edge 56 and a rear edge 58. In a preferred embodiment, the trailing edge is defined by a chamfered surface 60. The hot seat 38 also includes a plurality of mounting holes 61 as best shown in FIG. The mounting holes 61 also include countersink holes 62 formed in the hot seat inner portion 50, as best shown in FIG.

  The spine structure 40 extends the length of the hot seat 38 and retains the shape of the hot seat. In the preferred embodiment, the spine structure 40 is made from metal. Further, in one aspect of the invention, as best shown in FIG. 3, the spine structure 40 includes a posterior support 63 that extends to the posterior portion 32 of the bifurcated flap 26. The spine structure 40 also includes a plurality of spine openings 64.

  With reference to FIGS. 5 and 6, the plow portion 46 includes a plow body 66 having a plow outer edge 72 and a plow inner edge 74 along with a plow outer surface 68 and a plow inner surface 70. The plow outer surface 68 and the plow inner surface 70 are shaped to minimize aircraft traces and provide optimum aerodynamic characteristics. In the engine stop state, the plow portion 46 does not coincide with the trailing edge 58 of the hot seat 38 as shown in FIG. More precisely, an offset 75 is provided between the plowed outer surface 68 and the chamfered surface 60 provided axially inwardly from the chamfered surface 60. Further, a gap 76 is formed between the hot sheet outer surface 52 and the plow inner edge 74. In a preferred embodiment, the plow portion 46 is made from CMC material.

  Referring to FIGS. 6-10, the plow portion 46 is attached to the spine structure by a plow fastener assembly 48. In a preferred embodiment, the plow portion 46 includes a mounting structure 77 for mounting the plow portion on the spine structure. As best shown in FIGS. 8 and 9, the mounting structure 77 includes a dovetail slot 80 formed in the mounting structure and a recess 82 formed in the plow portion. ,including. The recess 82 includes a substantially flat recess surface 83 and a recess wall 84. Dovetail shaped slot 80 includes a bottom slot surface 85 and a wedge slot surface 86.

  With reference to FIGS. 7 and 8, the plow fastener assembly 48 includes a plow fastener 94, a nut 96, and a bracket 98. The plow fastener 94 includes a base portion 104 and a protruding portion 106 extending from the base portion. The protrusion 106 includes a far end 108 and a root portion 110, and the far end 108 is provided with a thread 114. The base 104 has a substantially trapezoidal shape and fits into the dovetail slot 80 of the plow portion 46. The fastener includes a radius 116 formed at the root 110 of the protrusion 106 of the fastener 94, as best shown in FIGS. The nut 96 is fixed to the thread 114 of the protruding portion 106 of the fastener 94. The bracket 98 includes a first side portion 118 and a second side portion 120 in which a rib 124 is formed. The ribs 124 are formed to fit into the recesses 82 in the plow portion 46, as best shown in FIGS. 8 and 9, and in a preferred embodiment the ribs 124 are openings provided in the bracket 98. It is formed on both sides of the portion 126. The opening 126 is suitable for allowing the protruding portion 106 of the fastener 94 to pass therethrough. A Belleville washer 128 can be selectively disposed between the bracket 98 and the nut 96.

  Referring to FIGS. 8-10, when the plow fastener 94 is inserted into the dovetail slot 80, a gap 130 (best seen in FIGS. 9 and 10) is formed between the base portion 104 of the fastener 94 and the dovetail slot 80. Is shown). The gap 130 and the radius 116 allow for thermal expansion of the fastener 94 and minimize the load on the plow CMC material. When the plow fastener 94 fits in the plow portion mounting structure 77, the rib 124 fits in the recess 82. The recess 82 includes a substantially flat recess surface 83 that houses the rib 124. The dish washer 128 holds a preload when the member is thermally expanded. Although one dish washer 128 is shown, a plurality of washers may be used.

  With reference to FIGS. 3, 4, 11, and 12, the attachment means 42 for attaching the CMC hot seat 38 to the spine structure 40 includes a fastener 134, a washer 136, a spacer 138, and at least one dish washer 140. And a nut 142. The fastener 134 includes a head portion 146 and a body portion 148 with a plurality of threads. The fastener 134 passes through the mounting hole 61 and the countersink 62 provided in the CMC hot seat 38. The fastener head portion 146 is received in the countersink 62. The washer 136 is sandwiched between the hot 38 and the spine structure 40 and supports the spacer 138. The spacer 138 includes a cylindrical portion 154 and a ring portion 156 extending outward from the cylindrical portion. The cylindrical portion 154 of the spacer is in the vicinity of the fastener body 148, and the ring portion 156 extends radially outward from the spine structure 40, and as best shown in FIGS. And a spacer gap 158 between the spine structure 40 and the spine structure 40. The length of the cylindrical portion 154 of the spacer 138 is longer than the thickness of the spine structure 40 provided in the cylindrical portion, and defines the gap 158. At least one dish washer 140 is provided radially outward from the spacer 138, and a nut 142 is tightened on the at least one dish washer 140 so that there is no looseness between the hot seat 38 and another member and a predetermined tight fit is achieved. All members can be fastened to the hot seat 38 in a loaded (preloaded) state.

  Referring back to FIG. 4, the spine structure 40 includes a plurality of spine openings 64 that allow the spine structure 40 to be attached to the hot seat 38. The spine opening 64 closest to the hinge assembly 36 is substantially circular and sized to accommodate the body portion 148 of the fastener 134, as shown in FIG. The other spine openings are slotted slots that allow movement of the spine structure 40 relative to the hot seat 38 as shown in FIG. Accordingly, the spine structure 40 is fixedly attached to the hot seat at the front portion 30 of the flap 26. However, the spine structure 40 can move freely in the axial direction and moves toward the rear portion 32 of the flap 26 when subjected to thermal expansion.

  During operation, once the engine 10 starts operation, the engine temperature rapidly rises from the ground ambient temperature to an extremely high temperature. The temperature of the gas 18 passing through the engine also rises to a very high temperature, creating a harsh environment for most gas turbine components. More specifically, when the engine 10 starts operation, the high-temperature gas 18 is exhausted from the exhaust nozzle 20, and the branch flap 26 is heated to an extremely high temperature. The hot seat 38 contacts the exhaust gas 18 passing through the engine. In particular, the hot sheet 38 is designed to withstand the high temperature. Although the CMC hot sheet is exposed to extremely high temperatures, the hot sheet does not expand significantly due to the material properties of CMC. However, the metal spine structure 40 is subject to greater thermal expansion. Thus, when the spine structure 40 expands, the plow portion 46 secured to the spine structure moves rearward toward the rear edge 58 of the hot seat 38. As the plow portion 46 moves relative to the trailing edge 58 of the hot sheet 38, the offset 75 is filled and substantially removed. When the spine structure is inflated, the plow outer surface 68 is generally coplanar with the chamfered surface 60 and the outer flap outer surface 28, as best shown in FIGS. The extremely high temperature also causes deflection and deformation of the rear portion 32 of the hot sheet 38. The rear support 63 of the spine structure 40 minimizes deformation of the trailing edge 58 of the hot seat 38. By minimizing the deformation, contact between the plow inner edge 74 and the hot sheet 38 is also minimized.

  In the plow fastener assembly 48, a dovetail shaped slot 80 holds the fastener 94 within the slot. The recess 82 provides a lock mechanism for preventing the fastener 94 from rotating and moving to the CMC sheet. The clearance between the base portion of the fastener 94 and the dovetail slot 80 allows the metal fastener to thermally expand without applying a load to the CMC material. The dish washer is provided between the nut and the mechanism to retain a preload when the member is thermally expanded, to reduce the rigidity of the fastener assembly, and to the CMC material generated by the thermal fastening of the assembly. Stress can be minimized.

  The plow fastener assembly 48 makes it possible to attach the CMC sheet to the metal structure without forming a through-hole shaped opening in the CMC sheet. This mechanism is particularly important in stealth aircraft designs where the aircraft outer surface is made of a special material and metal fasteners must not be disposed on the surface. In addition, this unique mounting structure realizes the connection between the CMC material and the metal structure without leakage, and eliminates the need to provide holes or openings. Furthermore, the fastener 94 is insulated from the high temperature side 50 of the CMC sheet 38, thus maintaining the integrity of the fastener. The plow fastener assembly 48 can be used to bond any CMC material to the metal structure. In one embodiment of the invention, the plow portion 46 is attached to the spine structure via the bracket 98 as shown in FIGS. The bracket 98 is made of metal and is then easily attached to the spine structure 40 by various general fastening means 160 such as rivets and bolts as shown in FIGS. Therefore, the bracket 98 serves as a bridge between the CMC sheet and another member to which the bracket is attached by a general fastening technique. However, in the specific case, the plow portion is attached directly to the spine structure 40.

  In a preferred embodiment, the bracket 98 is provided between the plow portion and the spine structure, but the plow portion 46 may be attached directly to the spine structure 40. However, the bracket 98 provides a bridge between the plow portion and the spine structure, so that the plow portion can be attached to any structure via the bracket by various common attachment means. In addition, in the preferred embodiment, the plow portion fastener assembly 48 is provided on a plane to accommodate thermal expansion and minimize thermal stress. The fastening means 160 for attaching the bracket 98 to the spine structure 40 is also provided on the plane so as to minimize thermal stress. Further, the spine structure 40 can be thermally expanded with respect to the hot seat 38 by the spine opening 64 formed in the slot structure and formed in the spine structure. Becomes movable toward the rear edge 56 of the hot sheet 38.

  The attachment means 42 makes it possible to attach the CMC material to other types of materials without damaging the CMC material while applying a large fastening force to the assembly. When the nut 142 is tightened on the fastener 134, the metal spine structure 40 is confined between the spacer 138 and the washer 134, and does not loosen between the CMC material and other members, and is tightly fitted. Under a predetermined preload, all the members are integrally clamped against the hot seat 38. An elongated slot 64 provided in the backbone structure 40 allows the backbone structure to be moved relative to the hot seat without loosening the mounting assembly 42. Dish washer 140 retains the preload and reduces the rigidity of the fastener assembly, thereby minimizing stress on the CMC material caused by thermal fastening of the assembly. The spacer allows for thermal expansion of the spine structure while maintaining a tight attachment of the assembly.

  Another advantage of the present invention is that the plow portion 46 fills the gap between the hot seat 38 and the outer flap 24. This feature ensures the smoothness of the entire engine profile and minimizes detection of the aircraft. Another advantage of the present invention is that the plow portion moves relative to the hot seat 38 to fill the offset 75 in high temperature conditions, further suppressing detection of the aircraft. Another advantage of the present invention is that the plow portion 46 is made from CMC material. The plow portion made from this CMC material can minimize aircraft traces. The above features of the present invention can also absorb the difference between the coefficient of thermal expansion of the CMC material and the coefficient of thermal expansion of the metal member. For example, the spine opening 64 allows relative movement between the spine structure 40 and the hot seat 38, and thus absorbs the difference between the thermal expansion coefficient of the metal material and the thermal expansion coefficient of the CMC material, and the plow portion. 46 moves toward the rear edge 56 of the hot seat 38, and even a small gap is eliminated as much as possible. Further, the trace of the aircraft can be improved. Another advantage of the present invention is that the rear portion 63 minimizes deformation of the hot seat 38. Another advantage of the present invention is that the CMC sheet can be attached to any material by the bracket 98.

  In addition, the present invention overcomes the difficulty of securing the CMC plow portion on the metal member. The plow fastener assembly 48 eliminates the need to form through holes in the outer surface of the engine and absorbs the difference in coefficient of thermal expansion between metal and CMC.

  One advantage of the attachment means 42 is that although the CMC panel is fastened with great force, sliding between the CMC panel and the metal structure is possible. In addition, it is possible to eliminate the rattling of the member in the opening, thereby suppressing the deterioration of the material and extending the useful life of the member. This fastening mechanism not only attaches the CMC member to a member of a different material, but also absorbs thermal expansion mismatch and fixes the CMC member under positive and negative pressure conditions. By the fastening mechanism, the structure can be slid with respect to the CMC panel so as to remove the thermal stress.

  While the invention has been disclosed and described in connection with specific embodiments, those skilled in the art will envision improvements in the invention without departing from the spirit and content of the invention.

1 is a schematic view of a gas turbine engine. FIG. 2 is a side view schematically showing a branch flap and an external flap of the gas turbine engine of FIG. 1. The schematic side view of the branch flap of FIG. 2 which also showed the cross section of the plow part. FIG. 4 is a plan view schematically showing the branch flap of FIG. 3. FIG. 4 is an enlarged partial view of the branch flap of FIG. FIG. 4 is an enlarged partial view of the branch flap of FIG. The disassembled perspective view which shows the outline of the plow fastener assembly which attaches the hot seat of a branch flap to a bracket. FIG. 8 is an exploded view of the plow fastener assembly of FIG. 7 joining the bracket and the hot seat. FIG. 9 is a cross-sectional view schematically illustrating the plow fastener assembly of FIG. 8 taken along line 9-9. FIG. 9 is a cross-sectional view schematically illustrating the plow fastener assembly of FIG. 8 taken along line 10-10. FIG. 5 is a cross-sectional view of a mounting fastener assembly that secures the spine structure and hot seat of the branch flap shown in FIGS. 3 and 4 and passes through a substantially circular hole. Sectional drawing of the attachment fastener assembly which fixed the backbone structure and hot seat of the branch flap shown to FIG. 3 and FIG. 4, and penetrated the slot of the long hole shape.

Explanation of symbols

24 ... External flap 26 ... Branch flap 38 ... Hot seat 40 ... Spine structure 46 ... Plow part 48 ... Plow fastener assembly 58 ... Trailing edge of hot seat 94 ... Plow fastener

Claims (18)

A flap assembly provided in an exhaust nozzle of a gas turbine engine,
A hot seat including an inner portion of the hot seat and an outer portion of the hot seat, which extends along the axial direction in the gas turbine engine;
A spine structure for supporting the hot seat, provided on the outer side in the radial direction of the hot seat and located in the vicinity of the outer portion of the hot seat;
A plow portion fixed to the backbone structure and filling a gap between the hot seat and an external flap;
With flap assembly.   The flap assembly of claim 1, wherein the plow portion has an outer shape that complements and substantially maintains the shape of the outer flap.   The flap assembly of claim 1, wherein the plow portion is made from CMC material to minimize aircraft detection.   The flap assembly of claim 1 wherein the plow portion and the hot seat are made from CMC material and the spine structure is made from metal.   When the spine structure is thermally expanded, the plow part is attached to the spine structure such that the plow part moves and minimizes the offset between the trailing edge of the hot seat and the plow part. The flap assembly according to claim 1 characterized in that:   The spine structure includes a plurality of openings, and some of the openings have a slot shape that allows relative movement between the spine structure and the hot seat, thereby providing the spine. The flap assembly of claim 1 wherein the plow portion moves axially when the structure is thermally expanded.   The flap assembly of claim 6, wherein the plow portion moves axially to minimize an offset between a trailing edge of the hot seat and the plow portion.   The flap assembly of claim 1, wherein the plow portion is secured to the spine structure by a plurality of fasteners.   The flap assembly of claim 8, wherein the plurality of fasteners are configured to minimize thermal stress.   The flap assembly of claim 8, wherein the plurality of fasteners are configured to be disposed on a plane.   The flap assembly of claim 1, further comprising a rear support extending axially from the spine structure toward a rear edge of the flap assembly to minimize deformation of the hot seat.   The flap assembly according to claim 1, wherein the rear support is cantilevered by the spine structure.   The flap assembly of claim 1, further comprising a plurality of fasteners for attaching the plow portion on the spine structure without requiring through holes in the plow portion of the flap.   The flap assembly of claim 13, wherein each of the plurality of fasteners is made of metal.   The flap assembly of claim 13, further comprising a bracket disposed between the plurality of fasteners and the spine structure. A branch flap assembly provided in an exhaust nozzle of a gas turbine engine,
A hot sheet including an inner portion of the hot sheet and an outer portion of the hot sheet, extending along the axial direction;
A spine structure for supporting the hot seat, provided on the outer side in the radial direction of the hot seat and located in the vicinity of the outer portion of the hot seat;
A plow portion fixed to the spine structure and made from CMC material;
Branch flap assembly with. A branch flap assembly provided in an exhaust nozzle of a gas turbine engine,
A hot sheet including an inner portion of the hot sheet and an outer portion of the hot sheet, extending along the axial direction;
A spine structure for supporting the hot seat, provided on the outer side in the radial direction of the hot seat and located in the vicinity of the outer portion of the hot seat;
A plow portion fixed to the spine structure and separated from the hot seat to fill a gap between the hot seat and an external flap;
Branch flap assembly with.   The bifurcated flap assembly of claim 17, wherein the plow portion is attached to the spine structure without providing a through hole in the spine structure.

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